Light-weight, high-strength composite structures are being employed in an ever-wider variety of applications, particularly where the benefits to be gained by use of such materials clearly offset the generally higher costs associated with them. One area of increasing use of composite materials is in the automotive components area where the light weight and high strength aspects of the composite materials can be translated into higher fuel efficiencies. Examples of such light-weight, high-strength components include leaf springs, stabilizer bars, body parts and the like.
Another potential automotive application for light-weight, high-strength composite structures is in reciprocating components such as pistons. Not only will light-weight pistons result in a reduction in dead weight, as in stationary components, but there is also a decrease in the mechanical loss that results by a reciprocating mass. For example, approximately 50% of the forces encountered by a reciprocating engine component is a result of the component's own weight. Therefore, a reduction in weight leads to a reduction in load and thus allows a further reduction in weight and increased efficiency.
New light-weight, high-strength pistons have potential utility also where engine performance is of paramount concern such as with racing vehicles. Lighter weight pistons can result in greater output for a given engine design. Even small engines used, for example, in chain saws and the like would be vastly improved by use of light-weight, high-strength components. The physical debilitating vibrations endured by the operator of such mechanisms can be significantly reduced by use of lighter weight pistons for such engines.
Despite this myriad of potential uses for such light-weight composite reciprocating components, there has been little progress in the area of developing a suitable light-weight piston due to the high temperatures and high repetitive loadings that such parts are subjected to. Thus, light-weight pistons have been made in the past from metals such as aluminum reinforced by steel. A drawback in such constructions, of course, is that at the temperatures prevailing in use the significant differences in the thermal expansion of the different materials, the aluminum and steel, result in additional problems which must be overcome to satisfactorily employ such hybrid structures.